"Sweat of the brow" doctrine has been rejected in most countries.[1] Even Europe's Database Directive, probably the closest thing to an implementation of this doctrine, largely doesn't do much in practice.

An example of "sweat of the brow" doctrine would be the series of "Beaches of ..." books by Andrew D. Short of the University of Sydney where significant sweat has been expended to visit and document every beach of Australia, particularly from a swimming safety perspective. That's a lot of very remote beaches, and many with crocodiles. Across the Northern extent of mainland Australia from Broome to Cooktown (this being one of the books in the series), 3500 beaches were visited and documented along 12000km of coastline.[2]

AI could train on these books and gain an understanding of whether some small and unknown beach that receives <100 visitors a year has fine sand composition, pebbles, etc. Without "sweat of the brow", this use of AI is completely fine to regurgitate the facts learned from the book (regardless of the accuracy of the book).

If "sweat of the brow" did exist, there would be some very significant (probably insurmountable) challenges to overcome, including:

1. You're a different expert in beaches and also want to visit all 3500 beaches across Northern Australia to provide a more up-to-date database, just in case beaches have changed in the last 10 years (e.g. sand washed away). In your database/book series, can you write "Andrew D. Short observed ACME Beach in 2006 to have fine sand. We observe 10 years later in 2026 the beach is now entirely pebbles of 15-20mm diameter", or is this infringing?

2. You're a researcher studying drowning deaths at Australian beaches and wish to extend the data published by Andrew D. Short's series of books with additional fields--dates of drownings at a beach, weather conditions on the day of drownings, etc, and then make some novel observations from the expanded dataset. Is this infringing?

3. You visit ACME Beach and observe and document it--what type of surface, dimensions, presence of reefs/rips/etc. You then put this information on your blog or social media account and it becomes a social media phenomenon as people are attracted to what has been revealed to be the best "secret" beach in the world. A few days later your website or social media account is blocked/deleted without warning--apparently there has been a complaint that you might have copied some facts out of a book you've never heard of.

"Sweat of the brow" doctrine would almost certainly result in a tragedy of the anticommons[3] situation which would be worse for humanity as a whole.

[1] https://en.wikipedia.org/wiki/Sweat_of_the_brow

[2] https://sydneyuniversitypress.com/products/9781920898168

[3] https://en.wikipedia.org/wiki/Tragedy_of_the_anticommons

I wasn't aware of the "sweat of the brow" doctrine until you mentioned it. But you seem to be using it incorrectly. The doctrine only states that creativity or originality isn't required to make a work copyright-able.

Even if this were an accepted principle, that wouldn't change the principle of free use. In all of your examples, only re-printing all or substantial portions of the books of Andre D. Short would be copyright violations. Just referencing facts from Short's books, or even including small quotes, in your own new work is not a violation.